‘Milky Way Blues’

Scientists often transform astronomy data in a way that allows for interpretation with visual plots such as color-coded graphs. UC Santa Barbara postdoctoral fellow Greg Salvesen went in a different direction. He decided to instead map raw data to sound to make the excitement of astronomy — a traditionally visual science — accessible to people with visual impairments. Salvesen’s recently launched website, Astronomy Sound of the Month or AstroSoM (pronounced “Astro Psalm”), features different sounds produced from actual astronomy data, along with a brief explanation written by an astronomer.
“AstroSoM explores how sound complements more traditional astronomy data analysis,” Salvesen said. “Besides, making sounds out of real astronomy data is just plain cool!”
For his latest feature, Salvesen collaborated with University of Massachusetts astronomy professor Mark Heyer to produce a piece called “Milky Way Blues” that allows listeners to “hear” how our galaxy rotates. Heyer created the sonification and Salvesen supplied the visualization, incorporating an existing image of our galaxy created by Robert Hurt of IPAC/Caltech. The combined efforts reduce complex data into visual and aural components that track the movement of gas through the galaxy.
“‘Milky Way Blues’ has a bit of a player piano look and feel to it, which is what we wanted,” Salvesen explained. “What you’re hearing is the rotation or the motion of gas in our galaxy.”
Radio telescopes observe different spectral emission lines to probe different phases of gas (atomic, molecular, ionized). Astronomers measure the Doppler shifts of these lines to determine gas velocities along the path that the telescope is pointing. To turn one of these observations into musical notes, the measured gas velocities are mapped to a pentatonic minor blues scale.
Each note and circle represents gas that is either coming toward Earth (high notes and blue color) or moving away from it (low notes and red color). Different gas phases …